I live in a 1920's three bed semi. I don't have damp walls but in the winter the windows were so heavy with condensation that I used a vax thing to hoover all the water off and getting a couple of tanks full. My humidity was in the house was generally over 70%. I therefore decided to try this gadget (I like gadgets). It was reasonably easy to fit despite some lathe and wattle ceilings and it looks quite unobtrusive in the hall. The first thing I noticed was that on high it really does cool the stair well and it is very noticeable noisy. However it did reduce the humidity into the low sixties. As time has gone on I have reduced the setting to 2 and it is no longer noticeable at all. The humidity has gradually come further down over the months and I am now routinely under 50%. I also only get condensation on the windows after very cold night. However, it is only about an inch at the bottom which clears itself quite quickly as the day warms up. I've had now had this for about six months and I really do think it's made a massive difference although you need to give it time. Definitely recommend.